Zinc oxide (ZnO) is perhaps one of the most widely studied material in the last two decades. It has received so much of attention because of its incredible potential for wide ranging applications. ZnO is a wide band gap semiconductor (Eg = 3.37 eV at 300 K) with a rather large excitonic binding energy (~60 meV). This combination of properties makes it an ideal choice for several optoelectronic devices that can easily work at room temperature. ZnO is a truly multifunctional material possessing several desirable electrical, optical, optoelectronic, and piezoelectric properties. In addition, it is highly amenable to production of various kinds of nanostructures such as nanorods, nanotubes, nanoribbons, nanoneedles, etc., which makes it even more desirable for nanoscale devices. Examples of ZnO based nanodevices could include photodiodes, photodetectors, nano-lasers, field-emission devices and memristors. In order to make such devices, one could need device quality nanostructures that must be reproducible and cost effective. Naturally, one has to look for a synthesis process that has great controls and is relatively inexpensive. The study provided here shows that among the various methods available for ZnO synthesis, the microwave-assisted chemical synthesis offers outstanding advantages in terms of rapid growth of nanostructures, economical use of energy and excellent controls of process parameters. In order to produce device quality ZnO nanostructures using microwave-assisted synthesis, one has to study the effect of various process parameters and optimise them for the desired growth. Therefore, in the current study, first, a systematic study was undertaken to synthesize ZnO nanostructures both in a aqueous and non-aqueous medium and their characterization was carried out in order to understand the effect of microwave power, time of irradiation, pressure, solvent and salt concentration, etc. The goal was to develop synthesis protocols for various kinds of nanostructures that could guarantee reproducibility, good yield, and device quality structures. This study has led to successful growth of ZnO nanostructures on various substrates, vertically aligned ZnO nanorods and templated arrays of desired structures, all with outstanding properties of the structures as confirmed by XRD, MicroRaman, photoluminescence, cathodoluminescence, FESEM, TEM, PFM studies and pole figure analysis. Piezoelectric force microscopy (PFM) and physical property measurement system (PPMS, Quantum Design), have been used to study the multifunctional properties of ZnO nanostructures. The PFM is a powerful technique to measure the local piezoelectric coefficient of nanostructures and nanoscale thin films. PFM works on the converse piezoelectric effect in which electric potential is applied and mechanical strain is measured using a cantilever deflection. The PFM (Brucker’s AFM dimension Scan Assist) was used to characterize individual ZnO nanorods. Extensive studies were carried out with PFM measurements and it was observed that the nanorods consistently showed high piezoelectric coupling coefficients (d33~50-154 pm/V). It was also found that the variation in d33 depended on morphology and size of nanostructure. The multifunctional properties were observed in small ZnO nanocrystals (NCs). Such high values of piezoelectric coupling coefficients open the door for novel ZnO based nanoscale sensors and actuators. The synthesized ZnO nanostructures were further optimized and characterized keeping in view three device applications namely Field emission, Memristors and Gas Sensors. The fabrication and characterization of these three devices with ZnO nanostructure was carried out using electron beam lithography and direct laser writing micromachining. Device fabrication using lithography involved several steps such as substrate cleaning, photoresist spin coating, pre-baking, post-baking, pattern writing, developing, sputtering/deposition of material for lift-off, ZnO growth, and overlay lithography. For field emission devices, high quality, well aligned, c-axis oriented ZnO nano-needles were grown on sputter coated Ti/Pt (20nm/100nm) on SiO2/Si substrate by rapid microwave-assisted method in aqueous medium. The diameter of the tip was found to be 1~2 nm and the length of the rod was approximately 3~5μm. For a particular batch the tip size, morphology, and lengths were found to be the same and highly repeatable. Pole figure analysis revealed that nanorods were highly oriented towards <002> direction. Field-emission measurements using the ZnO nanoneedles arrays as cathode showed very low turn-on electric field of 0.9 V/μm and a very high field enhancement factor ~ 20200. Such a high emission current density, low turn-on electric field, and high field enhancement factor are attributed to the high aspect ratio, narrow tip size, high quality and single crystallinity of the nanoneedles. The high emission current density, high stability, low threshold electric field (0.95 V/μm) and low turn-on field make the ZnO nanoneedle arrays one of the ideal candidates for field-emission displays and field emission sensors. In the suitability of ZnO nanostructures for memristor application it was found that the single crystalline ZnO nanorods were not suitable as they did not show memristive behaviour but the ZnO nanorods with native defects exhibited considerable memristive behaviour. Therefore the microwave-assisted grown ZnO nanorods with defects were used to fabricate memristive devices. Single and multiple ZnO nanorods based memristors were fabricated using electron beam lithography. These devices were characterized electrically by measuring the hysteresis in the I/V characteristics. A high degree of repeatability has been established in terms of growth, device fabrication, and measurements. The switching in single nanorod based devices was found to have “ON-to- OFF” resistance ratio of approximately 104 and current switching ratio (ION/IOFF) of 106. Gas sensing based on electrical resistance change depends on absorption and desorption rate of gases on the analyte which is governed by surface properties, morphologies and activation energy. Therefore, various morphologies of nanostructure were grown for gas sensing application. Through experimentation, the emphasis shifted to c-axis oriented ZnO nanostructures on SiO2 substrate for gas sensing. The c-axis orientation of ZnO nanostructures was preferred mainly due to its huge surface area. The measurements showed that the c-axis oriented ZnO nanorods were excellent hydrogen sensors, able to detect H2 as low concentration as 2 ppm, even when the sensing temperature is as low as 200 ˚C. However, oxygen sensing was achieved at a higher temperature (300 ˚C). Thus, the study undertaken in this thesis presents a microwave based rapid and economical method for synthesizing high quality, device grade ZnO nanostructures, their extensive characterization that shows the multifunctional properties of these structures, and there examples of varied device applications of the synthesized nanostructures as field emitters, memristors, and gas sensors.

Le but de cette thèse a été de fabriquer des réseaux de nanofils et de nanotubes de l’oxyde de zinc (ZnO) de dimensions contrôlées en utilisant la méthode de réduction électrochimique de l’oxygène moléculaire. Plusieurs approches concernant le contrôle des dimensions de ces nanofils ont été investiguées. Des réseaux formés de nanofils de ZnO ont été obtenus dans une large gamme de diamètre (25-500 nm), de longueur (0,25-10 µm) et de densité (1x108-8x109 nanofils/cm2). Après l’étude du mécanisme de formation des nanofils, nous avons proposé une nouvelle méthode pour obtenir des réseaux de nanotubes de ZnO par dissolution des coeurs des nanofils. Les dimensions des réseaux de nanotubes ont été contrôlées en contrôlant celles des nanofils lors de la première étape d’électrodépôt. Nous avons aussi montré que les épaisseurs des parois de ces nanotubes peuvent aisément être contrôlées par l’ajout d’une troisième étape d’électrodépôt. Les propriétés optiques, électriques et structurales des nanofils et des nanotubes de différentes dimensions, obtenus avec différents conditions de dépôt ont été étudiées dans cette thèse. Finalement, des cellules ETA, constituées de ZnO/CdSe/CuSCN, ont été étudiées en utilisant les réseaux obtenus. Les effets de la morphologie et des dimensions des nanofils et nanotubes sur la diffusion de la lumière et la performance électronique des dispositifs ont été étudiés. Cela nous a permis de mieux comprendre les mécanismes optiques et électroniques impliqués dans ce type de cellule solaire ouvrant de nombreuses possibilités pour améliorer leur performance / The goal of this thesis was to obtain arrays of zinc oxide (ZnO) nanowires and nanotubes with tailored dimensions. For this purpose, the formation mechanism of ZnO nanowire arrays by electroreduction of molecular oxygen was studied and several approaches concerning the control of nanowire dimensions were proposed. Arrays of ZnO nanowires with a wide range of diameter (25-500 nm), length (0.25-10 µm) and density (1x108-8x109 nanofils/cm2) were obtained. After the study of ZnO nanowires formation mechanism, we have proposed a novel method for obtaining arrays of ZnO nanotubes by etching the nanowire cores. The nanotube dimensions were controlled by controlling those of the nanowires in the first electrodeposition step. We have also tuned the wall thickness of the nanotubes by adding a third electrodeposition step. The optical, electrical and structural properties of ZnO nanowires and nanotubes with different dimensions obtained with various parameters were studied. Finally, ETA solar cells, constituted of ZnO/CdSe/CuSCN, were studied by using ZnO nanowire and nanotube arrays. The effects of the morphology and dimension of the ZnO 1D nanostructures on the light diffusion and the electronic performance of the devices were studied. This allowed us to gain further insight into the optical and electronic mechanisms involved in the ETA solar cells opening numerous possibilities to improve their performance

Recently, efforts have been made for self-powering the batteries and portable electronic devices by piezoelectric nanogenerators. The piezoelectric nanogenerators can work as a power source for nano-systems and also as an active sensor. The piezoelectric nanogenerator is a device that converts random mechanical energy into electrical energy by utilizing the semiconducting and piezoelectric properties. Also, the mechanical energy is always available in and around us for powering these nano devices. The aim of the present thesis work is to explore 1D and 2D ZnO nanostructures (nanorods and nanosheets) on metal alloy substrates for the development of piezoelectric nanogenerators in energy harvesting and sensors applications. Hydrothermal synthesis method was adopted for the growth of ZnO nanostructures. The nanogenerators were fabricated by using the optimized synthesis parameters and subsequently studied their performance for power generation and as an active speed sensor. These 1D and 2D nanostructures based nanogenerators have opened up a new window for the energy harvesting applications and sensors development. The thesis is divided into following six chapters. Chapter 1: This chapter gives a general introduction about energy harvesting devices such as nanogenerators, available energy sources, mechanical energy harvesting, ZnO material and the details on hydrothermal synthesis process. A brief literature survey on different applications of piezoelectric nanogenerators is also included. Chapter 2: A novel flexible metal alloy (Phynox) and its properties along with its applications are discussed in this chapter. Details on the synthesis of 1D ZnO nanorods on Phynox alloy substrate by hydrothermal method are presented. Further, the optimization of parameters such as growth temperature, seed layer annealing and substrate temperature effects on the synthesis of ZnO nanorods are discussed in detail. As-synthesized ZnO nanorods have been characterized using XRD, FE-SEM, TEM and XPS. Chapter 3: It reports on the fabrication of piezoelectric nanogenerator on Phynox alloy substrate as power generating device by harvesting the mechanical energy. Initially, the performance of the nanogenerator for power generation due to finger tip impacts was studied and subsequently its switching polarity test was also carried out. Output voltage measurements were carried out using the in-house developed experimental setup. Stability test was also carried out to see the robustness of the nanogenerator. Finally, the output voltage response of the nanogenerator was studied for its use as an active speed sensor. Chapter 4: Synthesis of Al doped 2D ZnO nanorsheets on Aluminum alloy (AA-6061) substrate by hydrothermal method is reported in this chapter. The optimized parameters such as growth temperature and growth time effects on the synthesis of ZnO nanosheets are discussed. As-synthesized ZnO nanosheets were characterized using XRD, FE-SEM, TEM and XPS. The Al doping in ZnO is confirmed by EDXS and XPS analysis. Chapter 5: Cost effective fabrication of Al doped 2D ZnO nanosheets based nanogenerator for direct current (DC) power generation is reported in this chapter. The performance of the nanogenerator for DC power generation due to finger tip impacts was studied and subsequently its switching polarity test was also carried out. Output voltage measurements were carried out using the in-house developed experimental setup. Stability test was also carried out to see the robustness of the nanogenerator. Finally, the DC output voltage response of the nanogenerator was studied for its use as an active speed sensor. Chapter 6: The first section summarizes the significant features of the work presented in this thesis. In the second section the scope for carrying out the further work is given.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The aim of this study was to develop a ZnO nanowire-array biosensor that would detect immunoglobulins and record changes in the concentration of an antibody. Early detection of disease-causing agents is essential for an early response. In contrast to conventional methods, biosensors may detect disease-associated agents much faster and more accurate, which holds specific benefits to rural communities. The development of such a biosensor would be favourable for diagnostics in underprivileged communities without infrastructure. The hypothesis was that binding of antibodies to the surface of ZnO nanowires would result in the generation of a piezoelectric potential that, when channelled through a Schottky barrier, would produce a constant voltage reading. Piezoelectricty would be generated due to the bending of the nanowires, or tensile stress applied to the nanowires due to binding of the antibodies. The performance of such a device largely depends on the methods used to construct the ZnO nanowires and methods used to funtionalize the sensor surface. The biggest challenge was thus to chemically modify the self-assembled monolayers (SAMs) and create intermediate monolayers that would react to primary amino groups of lysozyme and form a covalent amide bond. Lysozyme was selected as model antigen, since its structure and reaction with antibodies has been well studied. Alkanethiol and dialkyl disulphides were used to form SAMs. Different SAMs were compared to select the absorbate that would bind the highest concentration of lysozyme. Lysozyme was best immobilized onto Au film layers in the presence of SAM 3-mercaptopropionic acid. Weakest immobilization was in the presence of combined SAM 11-mercaptoundecanoic acid/1-nonanethiol. The sensitivity of the constructed ZnO nanowire biosensor was tested in vitro, in the presence of different concentrations of lysozyme antibodies. An increase in the dimension of the ZnO seed layer led to an increase in the mean diameter of the ZnO seed grains, and subsequently an increase in the mean diameter of the synthesized ZnO nanowires. Deposition of the ZnO seed layer, using the RF cylindrical magnetron sputtering technique, improved the c-axis alignment of the nanowires and produced nanowires with similar dimensions. However, deposition of the ZnO seed layer using the sol-gel spin coating technique, produced nanowires with irregular c-axis alignments and irregular diameters. An increase in the Au film thickness led to a decrease in the mean diameter of the synthesized ZnO nanowires and worsening of the c-axis alignment. In contrast to single crystalline Au (111) film layers, polycrystalline Au layers increased the mean diameter of the synthesized nanowires. The crystal orientation of the Au film layer had no effect on the c-axis alignment. Increased voltage readings were recorded with an increase in antibody binding, indicating that the ZnO nanosensor may be used to record changes in immunoglobulin levels. Antibody concentrations ranging from 10 ng/ml to 20 μg/ml were sensed. This is the first study showing that ZnO nanowires, conformed into piezoelectric transducers, may be used in the detection of antibodies. The current size of the chip with ZnO nanowires is approximately 1 cm², which is too big to incorporate into a compact monitoring device. Apart from the challenge to produce smaller nanowire-arrays, highly sensitive sensors and miniature amplifiers will have to be developed to increase the strength of the signals generated by the nanowires. The biosensor will also have to be optimised to detect a variety of immunoglobulins. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om ‘n ZnO nanodraad biosensor te ontwikkel wat immunoglobuliene kan opspoor en veranderinge in konsentrasies van die teenliggaampies sal reflekteer. Vroë deteksie van siekte veroorsaakende agente is belangrik vir n vroeg tydige respons. In teenstelling tot konvensionele metodes, kan biosensors siekte veroorsaakende agente vining en akkuraat opspoor, wat veral voordele vir gemeenskappe in landelike gebiede inhou. Die hipotese was dat binding van teenliggaampies aan die ZnO nanodrade ‘n piëzo-elektriese potensiaal sal skep, wat dan ‘n konstante leesbare spanningspotensiaal sal lewer nadat dit deur ‘n Schottky versperring gestuur is. Piëzo-elektrisiteit word gegenereer deur die buiging van die nanodrade, of deur spanning wat op die nanodrade geplaas word deur binding van die teenliggaampies. Die sukses van die ontwerp hang grootliks af van die metode wat gebruik word om die ZnO nanodrade te konstrueer en metodes wat gebruik word om die sensor oppervlak te funksionaliseer. Die grootste uitdaging was dus om die monolae wat outomaties saam groepeer (SAMs) chemies so te verander dat intermediêre monolae vorm wat aan primêre aminogroepe van lisosiem bind ten einde kovalente amied-bindings te vorm. Lisosiem is as model antigeen geselekteer omdat die struktuur en reaksie daarvan met teenliggaampies reeds goed bestudeer is. Alkaantiol en di-alkiel disulfied is gebruik om SAMs te vorm. ‘n Verskeidenheid SAMs is vergelyk ten einde die anker te selekteer waaraan die hoogste konsentrasie lisosiem sal bind. Lisosiem is die effektiefste aan Au film lae ge-immobiliseer in die teenwoordigheid van SAM 3-merkapto-propanoësuur. Die swakste immobilisasie is in die teenwoordigheid van kombineerde SAM 11-merkapto-dekanoësuur/1-nanotiol waargeneem. Die sensitiwiteit van die ZnO nanodrade is in vitro getoets, in die teenwoordigheid van verskillende konsentrasies van lisosiem teenliggaampies. ‘n Toename in die dimensie van die ZnO grondlaag het die gemiddelde deursnit van die ZnO grein verhoog en so ook die gemiddelde deursnit van die gesintetiseerde ZnO nanodrade. Toediening van die ZnO grondlaag deur gebruik te maak van die RF silindriese mikrogolf-verstuiwings tegniek het die orientasie van die c-aslyn van die nanodrade verbeter. Toediening met die sol-gel draai-bedekkings tegniek het ‘n onreëlmatige orientasie van die c-aslyn teweeg gebring, asook ‘n variasie in die afmetings van die nanodrade. ‘n Toename in die Au laag het ‘n afname in die gemiddelde afmetings van die nanodrade en ook ‘n onreelmatige oriëntasie van die c-aslyn veroorsaak. In teenstelling met enkel-kristallyne Au (111) het poli-kristallyne Au lagies ‘n toename in die gemiddelde deursnit van die nanodrade veroorsaak. Die kristal-oriëntasie van die Au laag het geen effek op die belyning van die nanodrade gehad nie. Die spanningspotensiaal het verhoog met ‘n toename in teenliggaampie binding. Hiervolgens kan die ZnO nanosensor gebruik word om veranderinge in immunoglobulien vlakke te monitor. Teenliggaampie konsentrasies wat wissel van 10 ng/ml tot 20 μg/ml is opgespoor. Hierdie is die eerste studie wat toon dat ZnO nanodrade, omskep tot piëzo-elektriese transduseerders, gebruik kan word in die opsporing van teenliggaampies. Die grootte van die skyfie met die ZnO nanodrade is tans ongeveer 1 cm² en is te groot om in ‘n kompakte biosensor in te bou. Benewens die uitdaging om kleiner nanodraad skyfies te ontwikkel, sal hoogs sensitiewe sensors en seinversterkers ontwikkel moet word om die sein afkomstig van die nanodrade te versterk. Die biosensor sal ook ge-optimiseer moet word om ‘n verskeidenheid immunoglobuliene op te spoor.

L'intérêt porté sur la miniaturisation des systèmes par la communauté scientifique est grand, que ce soit pour des raisons de mobilité, d'économie d'énergie ou d'innovation technologique. L'objectif de cette thèse est de déterminer les caractéristiques physiques et structurales des couches minces et des nanofils d'oxydes métalliques synthétisés par la méthode électrochimique. La première partie de cette thèse est consacrée à l'oxyde de bismuth en phase delta. Les couches minces élaborés par électrochimie sont de très bonne qualité cristalline, et seul la phase delta- Bi2O3 est présente. Le caractère nano structuré des couches minces est mis en évidence par les expériences de microscopie électronique en transmission (MET) et participe à la stabilisation de cette phase à température ambiante. Les mesures de conductivité réalisées par spectroscopie d'impédance complexe montrent un comportement différent selon la nature du substrat utilisé. Nous observons une excellente conductivité électrique des dépôts réalisés sur les substrats en argent doré (4*10-3 S*cm-1), alors que les dépôts obtenus sur l'inox montre un comportement très résistif (10-7 S*cm-1). La seconde partie de cette étude concerne l'oxyde de zinc. Les conditions d'élaboration par électrochimie influence les propriétés structurales et physiques des couches minces obtenues. Les différents traitements thermiques réalisés sur les couches minces de ZnO ont permis d'améliorer la qualité optique des couches et de modifier la structure du ZnO par incorporation d'azote lors de recuit dans l'ammoniaque. La dernière partie est consacrée à la synthèse et à la caractérisation de nanofils de ZnO élaborés par la méthode " template ". Cette méthode nous a permis de confiner la croissance par électrochimie dans des pores de différents diamètres. Les observations réalisés par MET et MET en Haute Résolution montrent que les nanofils obtenus sont monocristallins et de bonne qualité. Les propriétés d'émission observées en PL sont très proches des propriétés d'émission des couches minces

Fabrication and characterization of a new kind of pressure sensor using self-assembly Zinc Oxide (ZnO) nanowires on top of the gate of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is presented. Self-assembly ZnO nanowires were fabricated with a diameter of 80 nm and 800 nm height (80:8 aspect ratio) on top of the gate of the MOSFET. The sensor showed a 110% response in the drain current due to pressure, even with the expected piezoresistive response of the silicon device removed from the measurement. The pressure sensor was fabricated through low temperature bottom up ultrahigh aspect ratio ZnO nanowire growth using anodic alumina oxide (AAO) templates. The pressure sensor has two main components: MOSFET and ZnO nanowires. Silicon Dioxide growth, photolithography, dopant diffusion, and aluminum metallization were used to fabricate a basic MOSFET. In the other hand, a combination of aluminum anodization, alumina barrier layer removal, ZnO atomic layer deposition (ALD), and wet etching for nanowire release were optimized to fabricate the sensor on a silicon wafer. The ZnO nanowire fabrication sequence presented is at low temperature making it compatible with CMOS technology.

Different methods were developed for the preparation of bulk ZnO substrates. Remarkable improvement on the surface, optical and crystalline quality of the bulk ZnO substrate was achieved. ZnO substrates with an atomically flat surface exhibiting terrace-like features were used as a substrate for GaN grown by MBE. High-resolution x-ray diffraction and low temperature PL results show that similar high quality GaN layers can be achieved on both annealed O-face and Zn-face ZnO substrates. The prospect of the device applications of GaN epitaxy on ZnO, including AlGaN/GaN MODFET structure on ZnO and GAN/ZnO based p-n junction were discussed.

In this thesis, we demonstrate in-situ scanning electron microscopy techniques for both electron beam lithography (EBL) and in-situ one dimensional nano materials electrical characterization. A precise voltage contrast image positioning for in-situ EBL to integrate nanowires into suspended structures for nanoswitch fabrication has been developed. The in-situ EBL eliminates the stage movement error and field stitching error by preventing any movements of the stage during the nanolithography process; hence, a high precision laser stage and alignment marks on the substrate are not needed, which simplifies the traditional EBL process. The ZnO piezoelectronics is also studied using nano-manipulators in scanning electron microscope. Methods to improve the contact have been demonstrated and the contacts between probe tips and the nanowires are found to have significant impact on the measurement results.

O presente trabalho tem o objetivo de investigar a obtenção de hidrogênio a partir de soluções de etanol em água, por fotocatálise, usando-se catalisadores a base de óxido de zinco (ZnO). Nestes estudos foram empregados cinco catalisadores ZnO, sendo um comercial e os demais preparados através de diferentes metodologias encontradas na literatura. Os catalisadores foram caracterizados por área BET, DRX e FRX, e a investigação preliminar da atividade destes catalisadores foi feita através de ensaios de degradação fotocatalítica de rodamina B em reator slurry em batelada, onde foram avaliadas a taxa de reação e a remoção de corante. Os ensaios para a produção fotocatalítica de hidrogênio foram realizados em um reator de quartzo, operado em batelada com catalisador em suspensão e atmosfera inerte de nitrogênio. A solução foi irradiada por uma série de seis lâmpadas compactas de luz negra. Ao longo dos testes, amostras das fases líquida e gasosa foram coletadas e analisadas para identificação do consumo de etanol e produção de hidrogênio usando-se, respectivamente, Carbono Orgânico Total (TOC) e Cromatografia Gasosa (GC). Resultados preliminares mostraram que os catalisadores ZnO comercial e sintetizado (ZnO Merck e ZnO-B) apresentam atividade fotocatalítica e desempenho similares aos do TiO2 para a degradação da rodamina B. Contudo, estes mesmos catalisadores mostraram-se pouco ativos para a produção fotocatalítica de hidrogênio, com desempenho bastante inferior ao do TiO2 nas mesmas condições. Foi possível observar que o maior rendimento em hidrogênio ocorre para baixas concentrações de catalisador (0,05 gL[elevado a potência menos]1) e elevadas concentrações de etanol, sendo pouco dependente do pH. / This work aims to investigate the hydrogen production from ethanol-water solutions through photocatalysis, using zinc oxide catalysts (ZnO). Five ZnO catalysts were employed in this work; one was a commercial catalyst, while the others were prepared according to different methodologies reported in the literature. The catalysts were characterized by BET, XRD and XRF, and the preliminary investigation of their activity was done by photocatalytic degradation of rhodamine B, through the evaluation of the reaction rate and dye removal. Tests for photocatalytic hydrogen production were carried out in a quartz slurry batch reactor under nitrogen, irradiated by a set of six compact UV light bulbs. During the tests, gas and liquid samples were collected and analyzed in order to identify the consumption of ethanol and hydrogen production using, respectively, Total Organic Carbon (TOC) and Gas Chromatograph (GC). Preliminary results showed that the synthesized and commercial ZnO catalysts (ZnO-B and ZnO Merck) present photocatalytic activity and performance similar to TiO2 for the rhodamine B degradation. However, the ZnO catalysts presented lower performance when compared with TiO2 for hydrogen production, under the same conditions. It was observed that the highest hydrogen yield occurs for low concentrations of catalyst (0.05 gL1) and high concentrations of ethanol, being less dependent on pH.

Orientadora: Talita Mazon. / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-graduação em Energia.